Radiofrequency transformer and circuits therefor



' Nov; 16

E. A. KUEN ET AL RADIOFREQUENCY TRANSFORMER AND CIRCUITS THEREFOR Filed Jan. 1925 pented Nov. 16, 1926 UNITED STATES PATENT OFFICE.

EUGENE A. KUEN, or CINCINNATI, oHIo, AND oLARENo L. PATTERSON, 0F DETROIT,

= MICHIGAN.

BADIOFREQIJ'ENGY TRANSFORMER AND CIRdUITS THEREFOR.

Application filed January This invention relates to a radio frequency transformer and circuit therefor which have been devised to produce a radio receiver of unusual merits, in which:

I An object'has been to produce a receiver which is unusually quiet and highly selective in its operation, and in which:

A further object is to produce a receiver with radio tubes of the construction employing two grid e'lementsi V Fig. 2 is a view similar to Fig. 1, but showing a modified form of transformer embodying the principles of our invention, in .connection with a circuit employing tubes having two grid elements, as in the circuit shown in Fig. 1.

Fig. 3 is a fragmental diagrammatic view showing the transformer employed in the circuit shown in Fig. 1, adapted to the usual three element or single grid tube.

Fig. 4 is a view similar toFig. 8, but showing the trzmsformer' employed in the circuit shown in Fig. 2, adapted to the usual three element or single grid tube.

lVe will first describethe transformers we have devised and will then describe the circuits in which they play such an important part. Thefirst transformer construction to be described is that shown in Figs. 1 and 3. This transformer, whichis of the radio frequency type, employs three windings, one of which is the usual primary which we have designated by' the reference letter P, the

other two windings being n the form of two separate secondaries which we have designated by the reference letters S and S. The actual arrangement ofthe primary and secondary coils may conveniently and preferably be such that the convolutions of the three coils lie concentrically with relation to each other, with one secondary located on each side of the primary winding. Inasmuch as each 0011 has its own terminals 26, 1925. Serial o. 4,715.

there will be a total ofsix terminals for each of our improved transformers as shown at 1, 1, l and 2, 2, 2 in Fig. 1. cause ofthe fact that'the terminals 1-, 1 of the secondary coils S, S" are, in the preferred circuit embodying our improved transformer, connected, as shown in Fig. 1, the number of terminals may readily bereduced to five if desired. The proportion of the windings in this form of our improved transformer is preferably such that the two secondaries are identical as to thenumber of turns and size of wire.

In the transformer shown in Figs. 2 and at the actual number of windings is but two, consisting of a primary P and a secondary S, but the secondary is tapped at its exact center as shown at 3, so that'the secondary is divided into two equal windings which proinasmuch as the secondary stillhas its two usual terminals 1 and 2, and the primary has its usual terminals 1 and, 2, the trans- However, be-

former as a whole has five terminals which I afford connection with one primary and two secondary windings as in the previously described transformer construction, if we 0on sider the connection of the two terminals S and S" of the secondaries as one terminal after they are connected.

-In 'the connection of our improved trans former which embodies" the form shown in Fig. 1, the circuit, as shown in this View,

I contemplates the use of a radio tube having two grid elements G and G". The terminal S is connected directly to the grid G while the terminal S is connected to grid G preferably through an interposed fixed condenserC. The terminal P is connected with the plate. of the preceding input tube with which the usual antenna and ground circuit connections are made, such other circuit details being merely generally designated by the terminal posts marked Input. In the drawing we have shown two steps of radio frequency amplification through the use of our improved transformer, although as many may be employed as d i'red. From theradio' frequency stages th's illustrated,

detector use. In the circuit a potentiometer or voltage divider may be employed and a rheostat It maybe inserted to control the tube filament illumination. The output of the circuit is from the terminals so designated, and the battery connections are made as lndicated at the proper terminal posts.v

In order to use the usual three element or single grid tube our improved double secon any transformer may be connected somewhat as shown in Fig. 3. In this connec tion the primary winding terminals are connected as has been previously described, and the secondary terminals S and S are connected in the same manner. Howeven the terminals S and S are connected by bringing them both together into the single grid Gr connection with the condenser C preferably interposed between the juncture of the terminal I and S of the secondary coil S, so thatonly the secondary S is affected by the condenser.v

In the use of a single grid tube for the circuit using the transformer embodying the form shown in Fig. 2, the terminals S and S, as shown in Fig. 4, are connected together into the single grid G with the condenser C located between the juncture of the terminals S and S so that only the portion of the secondary between terminals S and S which is affected by the'tap taken off at terminal S will be controlled preferabl by condenser C. V

The use of'a double grid tube in connection with the transformer shown in Figs. 2 and 45, is clearly shown in Fig. 2. The terminal S is connected with. one grid G while the terminal S is connected with the other grid G preferably through the condenser C as shown. All other features of the circuit are identical with that shown in Fig. land need not be specifically described other than to point ,out that there-is but one secondary terminal 1 one each transformer to be connected to the input an. voltage divider V, instead of two as in Fi 1.

' The functioning of our improved transformer and circuit may be quite obvious to those skilled in the art, but it may be well to set forth briefly the general principle of operation involved. By subjecting each of the seco dary windings to identically the same input and potentiometer controlled voltage conditions through duplicate connections at terminals 8' and S in the form of the transformer shown in Fig. 1,- these coils will respond inthe same. manner. However, the action of coil S" will be held back somewhat and allowed to' issue in a more smooth manner by the "action of condenser C so that the objcctionableimpulses of energy received from the antenna circuit will'be ironed out as it were. One secondary will operate to allow these impulses to pass freely while the other, due

to its condenser connection, will operate to hold the impulses in a slightly retarded condition and allow them to issue with less blast than the other, much as the muflier of an internal combustion engine allows complete exhaust-ion to take place, but over-- ,comes the objectionable noise of explosion; This effect also assists the functioning of secondary S by bringing about a stepping of the energy impulses slightly out of phase through the-retarding action of one tube overthe other, thus, in a measure producing a neutralization which has noticeably beneficial' results in" the clearness, tone and volume of the signal reception.

Notonly is signal reception very materially improved in this manner, but the re ception of such disturbing influences as stat ie discharges, local interference through reradiating receivers, leakage of power transformers, sparking commutators and similar annoying sources of' trouble of this nature, is

substantially eliminated.

The transformer shown 1n Figs. 2 and 4 operates in identically the same manner be,

cause its central secondary winding tap produces in effect two secondary coils which function identically, one of which however, may be controlled in a measure by the condenser C as has been explained above.

Having thus described our invention what we claim is: I

1. In a wave signal responsive circuit, a radio tube,,a transformer containing a pri- -1nar windin' and twosecondar windin 's said primary winding having connection at one'terminal to the plate of-the tube and at its opposite end" to a source of plate potential, said secondary windings connected together at one terminal and to the filament circuit of the tube at their joined terminals,

the opposite terminals of the secondary windings having connection with thegrid circuit of the tube, one of said opposite sec ondary terminals having a condenser interposed in its connection with the grid circuit.

2. In a .wave signal responsivecircuit, a radio tube having two grids, a transformer containing a primary winding and two secondary windings,-said primary winding having connection with the plate circuit of .the

tube. one of the secondar windin s havin direct connection with one of the grids of having connection withthe circuit of one of terminal of the second mentioned secondary the grids of the tube, and a condenser conto the other grid of the tube. nected with the terminal of the other second- In testimony whereof we have hereunto 10 ary corresponding to the terminal of the fliX d Our Signatures;

5 first mentioned secondary connected with v the first mentioned grid, said condenser hav- EUGENE A. KUEN. ing connection with and connecting the grid CLARENCE L. PATTERSON. 

